Seemingly small changes in local weather patterns can have a big impact on growing conditions out at sea.

This includes:

  • Unseasonably mild winters
    Allowing water-borne bugs and challenges to persist where otherwise they would have been killed off by colder temperatures
  • Extreme rainfall
    Creating increased surface run-off from terrestrial users
  • Prolonged dry spells
    Affecting oxygen, salinity and nutrient levels in seawater
  • Increases in seawater temperatures
    Encouraging plankton, parasites and other health challenges
  • Oceanic conditions
    Driving north higher numbers of harmful micro-jellyfish.

The net effect of these changes, for salmon farmers, can be acute biological challenges resulting in higher than average fish mortalities, lower than forecast harvest volumes and reduced annual survival.

Mitigation measures

Realistic that the environment will continue to change, and determined to mitigate the impact of these changes, we’re putting the lessons learned into action across the full salmon lifecycle.

Watch our quick video below or read on to find out more.

Enhancing egg quality and survival

Incubation unit, Barcaldine Hatchery

Giving our fish the best start possible has long been core to our farming approach – the scope of what’s possible, however, continues to evolve and grow.

Recent years have seen us embark on several pioneering initiatives to boost egg quality and survival.

Targeted egg supply

We source our eggs from a range of suppliers who specialise in selecting the genetic traits most suited to the Scottish marine environment.

Thanks to a collaboration with one such specialist, AquaGen, this also includes sourcing eggs from fish known to have thrived at our own marine farms around Scotland’s west coast and Northern Isles.

These eggs are hatched and reared at our Barcaldine Hatchery then transferred to sea pens, where, once again, we select the best performers to produce offspring, continuing the cycle.

Our aim? To build a secure supply of high-quality eggs able to resist the health challenges that the changing environment can give rise to.

Bespoke incubation unit

Building on our £58M investment in our Barcaldine Hatchery, work is now underway on a £2M incubation unit adjacent to the main facility that will enable us to receive eggs even earlier in the process.

Currently, we receive fertilised eggs that have developed to the eyed stage.

Once the new unit is completed (expected Q4 ’23) we’ll be able to receive eggs prior to fertilisation, giving us greater control over key welfare factors – water quality, temperature, incubation period included – even earlier in the lifecycle.

£2M upgrade of Girlsta Hatchery

Acquired as part of our purchase of Grieg Seafood Shetland, our Girlsta Hatchery has the capacity to produce up to 3.5M smolts annually.

Now, we’re nearing completion (Q4 ’23) on a £2M upgrade of the facility, targeted at growing bigger, more robust smolts that can better withstand the challenges of the natural environment once at sea.

Boosting post-smolt survival

Smolt being weighed, Barcaldine Hatchery

Complementing our drive to improve egg quality and survival, we’re now looking to boost survival at the next key stage of the salmon lifecycle: the post-smolt stage when young salmon are ready to transition from freshwater to seawater.

Post-smolt facility

Thanks to the advances made in our freshwater farming, we’ve been able to grow smolts to more than twice the average weight achieved via traditional methods, reducing the time required at sea by up to two months.

Now, we’re now looking to shorten the marine cycle even further by investing in a post-smolt facility.

With planning permission to build this new facility at our Barcaldine Hatchery already secured, we’re currently evaluating both sea and land-based options capable of delivering 500g+ smolts and reducing the marine stage by a further three months.

Revising smolt input stocking plans

Across all three of our freshwater hatcheries – Barcaldine, Knock and Girlsta – we have revised our smolt input stocking plans to ensure:

  • Smolts are transferred from hatchery to marine farms at a period in the year that will minimise their exposure to challenges
  • Farms that have experienced isolated challenges are reconfigured to ensure swift intervention, should it be required
  • Farms that have experienced repeated challenges are rested until further research can be done.

Improving growing conditions

Fishnish, Isle of Mull

Streamlining our farming estate

Key to enhancing fish survival at sea is ensuring we’re farming in the best locations possible.

Helping us determine these ‘best of the best’ locations, we’ve completed extensive hydrodynamic modelling across our farming estate.

That done, we’re now busy streamlining our existing farming licences into a smaller number of locations, each with fewer pens but of a larger size.

This is enabling us to:

  • Increase the space between pens
  • Maximise water exchange and oxygen levels in and around pens
  • Minimise the impact of environmental challenges that can pass through farms
  • Boost fish health, welfare and survival
  • Improve operational efficiencies
  • Grow our harvest volumes.

Since 2021, we have consolidated and modernised 14 farms with another five planned for early 2024.

Exploring the potential of aeration

This farming year has seen us explore the potential of aerations systems to help mitigate some of the impacts of climate change.

Deployed on farm during periods of reduced oxygen, algal blooms or micro-jellyfish events, these systems draw water from the depth of the pen – in other words, away from the surface layers where blooms are typically more abundant – and distribute it upwards in short pulses, boosting the water quality of the whole pen.

Based on positive initial results with regards to fish feed rates, growth and overall welfare, we’re now investing in more of these systems for further exploration and analysis.

Increasing treatment capacity

Ronja Kvaløy at Cliftsound, Shetland by John Henderson

Being able to carry out treatments and interventions swiftly can make all the difference to fish health, welfare and survival.

It’s why we’ve been steadily adding to our fleet, resources and capacity.

In 2023 alone we have added:

  • Two new freshwater treatment vessels, the Inter Caledonia and Ronja Kvaløy (pictured), each with reverse osmosis technology capable of producing freshwater from seawater to help protect gill health
  • A second thermo delousing vessel, the Eloise Eslea, to help control sea lice levels and remove these naturally occurring parasites from the marine environment.

We’re also looking to introduce new technology which can be added to our freshwater vessels and enable us to gently delouse fish at the same time as protecting their gill health, reducing handling.

Enhancing environmental monitoring

Fish health lab, Lerwick
Fish health lab, Lerwick

Helping ensure we can make the most informed decisions about how best to protect fish health, each of our farms is equipped with new environmental surveillance tools.

Used daily – and even more frequently if a potential threat is detected – these tools provide our farming and fish health teams with an accurate insight into water quality at each location.

Mitigation strategy

In the event of an environmental threat being detected, we have a range of mitigation measures to deploy.

The single best approach, or combination of approaches, will depend on the nature of the challenge, but can include:

  • Managing feeding regimes to calm fish metabolism and reduce the volume of water-borne harmful plankton passing over their gills
  • Boosting water movement and quality by deploying aeration systems
  • Pausing any pre-planned interventions or handling
  • Transferring fish to alternative sites.

If, despite everyone’s best efforts to manage the situation, the environmental challenge persists, then the best decision in the interests of fish welfare may be to harvest out early.

Increasing processing capacity

Processing and packing facility, Lerwick

In anticipation of growing our harvest volumes, we have upgraded our two processing and packing facilities.

Following a £2M investment, our ‘facility of the future’ at Lerwick in Shetland has an annual capacity of 50kt – with scope to increase this further.

Meanwhile our South Shian facility near Oban now has an annual capacity of 30kt.

Built into both facilities is spare capacity to ensure that, should we decide to harvest early to protect fish welfare, we are able to move swiftly.